ARMONK, N.Y. (AP) — New York Gov. Andrew Cuomo's (KWOH'-mohz) ex-wife, Kerry Kennedy, plans to plead not guilty at her arraignment on a drug-impaired driving charge.

Kennedy is the daughter of Sen. Robert F. Kennedy and niece of President John F. Kennedy.

Police say she was arrested Friday after her car struck a tractor-trailer on an interstate north of New York City and she took an exit off it. They say an investigation found she was impaired by drugs.

A spokesman for Kennedy says breath, blood and urine tests revealed no drugs or alcohol in her system. Her lawyer says she'll plead not guilty Tuesday night.

Kennedy's sister-in-law Mary Kennedy hanged herself in May. Her brother Douglas Kennedy is fighting charges stemming from his attempt to take his newborn son from a maternity ward.